Automatic wafer edge inspection and review system

ABSTRACT

A substrate illumination and inspection system provides for illuminating and inspecting a substrate particularly the substrate edge. The system uses a light diffuser with a plurality of lights disposed at its exterior or interior for providing uniform diffuse illumination of a substrate. An optic and imaging system exterior of the light diffuser are used to inspect the plurality of surfaces of the substrate including specular surfaces. The optic can be rotated radially relative to a center point of the substrate edge to allow for focused inspection of all surfaces of the substrate edge.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 11/417,297, filed on May 2, 2006, entitled “SubstrateIllumination and Inspection System”. The disclosure of the aboveapplication is incorporated herein by reference.

FIELD

The present disclosure relates to illumination and inspection of asubstrate, particularly illumination and inspection of specular surfacesof a silicon wafer edge with diffuse light from a plurality of lightsources for enhanced viewing of the wafer edge.

BACKGROUND

The statements in this section merely provide background informationrelated to the present disclosure and may not constitute prior art.

Substrate processing, particularly silicon wafer processing involvesdeposition and etching of films and other processes at various stages inthe eventual manufacture of integrated circuits. Because of thisprocessing, contaminants, particles, and other defects develop in theedge area of the wafer. This includes particles, contaminants and otherdefects such as chips, cracks or delamination that develop on edgeexclusion zones (near edge top surface and near edge back surface), andedge (including top bevel, crown and bottom bevel) of the wafer. It hasbeen shown that a significant percentage of yield loss, in terms offinal integrated circuits, results from particulate contaminationoriginating from the edge area of the wafer causing killer defectsinside the FQA (fixed quality area) portion of the wafer. See forexample, Braun, The Wafer's Edge, Semiconductor International (Mar. 1,2006), for a discussion of defects and wafer edge inspectionmethodologies.

Attempts at high magnification inspection of this region of the waferhave been confounded by poor illumination of these surfaces. It isdifficult to properly illuminate and inspect the edge area of anin-process wafer. An in-process wafer typically has a reflectivespecular (“mirror”) surface. Attempts at illuminating this surface froma surface normal position frequently results in viewing reflections ofsurrounding environment of the wafer edge thus making it difficult tovisualize defects or distinguish the defects from reflective artifact.Further, the wafer edge area has a plurality of specular surfacesextending from the near edge top surface across the top bevel, thecrown, the bottom bevel to the near edge bottom surface. These too causenon-uniform reflection of light necessary for viewing the wafer edgearea and defect inspection. In addition, color fidelity to observedfilms and contrast of lighting are important considerations for anywafer edge inspection system.

Therefore, there is a need for a system that adequately illuminates theedge area of a wafer for inspection. It is important that the systemprovide for illumination and viewing suitable for a highly reflectivesurface extending over a plurality of surfaces and for a variety ofdefects to be observed. The system must provide for efficient andeffective inspection of the edge area for a variety of defects.

SUMMARY

Further areas of applicability will become apparent from the descriptionprovided herein. It should be understood that the description andspecific examples are intended for purposes of illustration only and arenot intended to limit the scope of the present disclosure.

The object of the present invention is to provide a color image-basededge defect inspection and review system. It comprises an illuminator toprovide uniform diffused illumination across the five wafer edgeregions: top near edge surface, top bevel, apex, bottom bevel and bottomnear edge surface, an optical imaging subsystem to image a portion ofwafer edge supported by a wafer chuck, a positioning assembly toorientate the optical imaging subsystem to the user-defined inspectionangle, an eccentricity sensor to actively measure the center offset of awafer relative to the rotation center of the wafer chuck, a wafer chuckto hold the backside of a wafer onto the supporting pins, a linear stageto move a wafer from its load position to the inspection position, arotary stage rotates the wafer in a step-and-stop fashion, a controlconsole to provide tool control functions as well as at least thefollowing capabilities: 1) automatic capture of defects of interest withenough sensitivity and speed, 2) automatic defect detection andclassification, 3) automatic measurement of wafer edge exclusion width;and 4) automatic report of inspection results to the yield managementsystem of a semiconductor fabrication plant.

In accordance with the present disclosure, a substrate illuminationsystem has a light diffuser with an opening extending at least a portionof its length for receiving an edge of a wafer. The system alsocomprises a plurality of light sources in proximity to the lightdiffuser. The system further comprises an optic for viewing the waferwherein the optic is exterior of the light diffuser and is angled off ofthe wafer edge surface normal position.

In an additional aspect, the system comprises an illumination controlsystem for independently controlling the plurality of light sources.Individually or by groups or sections, the plurality of lights can bedimmed or brightened. In addition, the plurality of lights can changecolor, individually or by groups or sections. Yet another aspect of thesystem comprises a rotation mechanism for rotating the optic from aposition facing the top of the wafer to a position facing the bottom ofthe wafer. In an additional aspect of the system, the plurality of lightsources is an LED matrix or alternatively a flexible OLED or LCD. Inthis aspect the flexible OLED or LCD can act in place of the pluralityof lights or in place of both the light diffuser and the plurality oflights. The light sources can also be one or more halogen lamps. The oneor more halogen lamps can be coupled to an array of fiber optics.

In yet an additional aspect, the system comprises a method for imagingthe specular surface of a substrate. This method comprises, isolating aportion of the substrate in a light diffuser, emitting light onto thespecular surface to be imaged and imaging the specular surface with anoptic positioned at an angle off the specular surface normal from aposition exterior to the light emitter.

DRAWINGS

The drawings described herein are for illustration purposes only and arenot intended to limit the scope of the present disclosure in any way.

FIG. 1 shows a schematic top view of the substrate illumination systemof the present disclosure;

FIG. 2 shows a schematic side view of the system as shown in FIG. 1;

FIG. 3 shows a detailed view of a portion of the view shown in FIG. 2;

FIG. 4 shows a schematic side view of an alternative embodiment of thesubstrate illumination system;

FIG. 5 shows a detailed view of a portion of the view shown in FIG. 4;

FIG. 6 shows a schematic side view of another alternative embodiment ofthe substrate illumination system;

FIG. 7 shows a perspective view of yet another embodiment of thesubstrate illumination system; and

FIG. 8 shows a top plan view of the alternative embodiment of thesubstrate illumination system as shown in FIG. 7;

FIG. 9 shows a perspective view of a wafer edge inspection and reviewsystem of the present disclosure;

FIG. 10 shows a cross section view of the illuminator shown in FIG. 9;

FIG. 11 shows a enlarged cross section view of the wafer edge regions;

FIG. 12 shows a schematic view of the optical imaging subsystem shown inFIG. 9;

FIG. 13 shows the inspection angles of the optical imaging subsystemshown in FIG. 9;

FIG. 14 shows the angle between the principal axis of the opticalimaging subsystem and the normal of the edge portion;

FIG. 15 illustrates the step-and-stop angular motion of a wafer;

FIG. 16 shows a user interface for semi-automated defect review;

FIG. 17 shows the process to review a specific defect of interest; and

FIGS. 18 and 19 show an example of edge exclusion measurement.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is notintended to limit the present disclosure, application, or uses. Itshould be understood that throughout the drawings, correspondingreference numerals indicate like or corresponding parts and features.

Referring to FIGS. 1, 2, and 3 a substrate illumination system 10 (the“system”) of the disclosure has a diffuser 12 with a slot 14 along itslength and a plurality of lights 16 surrounding its exterior radialperiphery. Exterior of the diffuser 12 is an optic 18 that is connectedto an imaging system 20 for viewing a substrate 22 as the substrate isheld within the slot 14. The plurality of lights 16 are connected to alight controller 34.

The system 10 can be used to uniformly illuminate for brightfieldinspection of all surfaces of an edge area of the substrate 22including, a near edge top surface 24, a near edge bottom surface 26, atop bevel 28, a bottom bevel 30 and a crown 32.

The optic 18 is a lens or combination of lenses, prisms, and relatedoptical hardware. The optic 18 is aimed at the substrate 22 at an angleoff a surface normal to the crown 32 of the substrate 22. The angle ofthe optic 18 advantageously allows for preventing a specular surface ofthe substrate 22 from reflecting back the optic 18 whereby the optic 18“sees itself.” The viewing angle is typically 3 to 6 degrees off normal.Some optimization outside of this range is possible depending onilluminator alignment relative to the substrate 22 and the specificoptic 18 configuration.

The imaging system 20 is for example a charge-coupled device (CCD)camera suitable for microscopic imaging. The imaging system 20 may beconnected to a display monitor and/or computer (not shown) for viewing,analyzing, and storing images of the substrate 22.

Diffuser 12 is formed of a translucent material suitable for providinguniform diffuse illumination. The diffuser 12 may be formed of a frostedglass, a sand blasted quartz or a plastic or the like, where lightpassing through it is uniformly diffused. In a preferred embodiment, thediffuser 12 is a circular cylinder as illustrated. Diffuser 12 may be anelliptic cylinder, generalized cylinder, or other shape that allows forsurrounding and isolating a portion of a substrate 22 including thesubstrate 22 edge. The slot 14 in the diffuser 12 extends for a suitablelength to allow introduction of the substrate 22 into the diffuser 12far enough to provide uniform illumination of the edge area and toisolate the edge area from the outside of the diffuser 12.

Importantly, the interior of the diffuser 12 serves as a uniform neutralbackground for any reflection from the specular surface of the substrate22 that is captured by the optic 18. Thus, the optic 18 while lookingtowards focal point F on the specular surface of the crown 32 images(sees) the interior of the diffuser 12 at location I. Similarly, theoptic 18 looking towards focal points F′ and F″ on the specular surfacesof the top bevel 28 and bottom bevel 30 respectively, images theinterior of the diffuser 12 at locations I′ and I″.

The angle of the optic 18 in cooperation with the diffuser 12 preventsreflective artifacts from interfering with viewing the plurality ofspecular surfaces of the edge area of the substrate 22. Instead, andadvantageously, a uniform background of the diffuser 12 interior is seenin the reflection of the specular surfaces of the substrate 22.

The plurality of lights 16 is a highly incoherent light source includingan incandescent light. In a preferred embodiment, the plurality oflights 16 is an array of LEDs. Alternatively, a quartz halogen bulb canbe the light source with fiber optics (not shown) used to distributelight of this single light source radially around the diffuser 12. Inanother preferred embodiment the plurality of lights 16 is an array offiber optics each coupled to an independent, remotely located quartztungsten halogen (QTH) lamp.

The plurality of lights 16 is preferably a white light source to providethe best color fidelity. In substrate 22 observation, color fidelity isimportant because of film thickness information conveyed by thin filminterference colors. If the substrate 22 surface is illuminated withlight having some spectral bias, the thin film interference informationcan be distorted. Slight amounts of spectral bias in the light sourcecan be accommodated by using filters and/or electronic adjustment (i.e.,camera white balance).

In operation, a substrate 22, for example, a wafer is placed on arotatable chuck (not shown) that moves the edge of the wafer into theslot 14 of the diffuser 12. The light controller 34 activates insuitable brightness the plurality of lights 16 for providing uniformillumination of the edge area of the wafer. The wafer is viewed throughthe imaging system 20 via the optic 18 and inspected for defects. Thewafer may be automatically rotated or manually rotated to allow forselective viewing of the wafer edge. Thus, observation of the wafer edgefor defects is facilitated and is unhindered by a specular surface ofthe wafer.

With added reference to FIGS. 4 and 5, in an embodiment of the system 10the plurality of lights 16 are individually controlled by the lightcontroller 34. In this embodiment light controller 34 is a dimmer/switchsuitable for dimming individually or in groups a plurality of lights.Alternatively, light controller 34 can be the type as disclosed in U.S.Pat. No. 6,369,524 or 5,629,607, incorporated herein by reference. Lightcontroller 34 provides for dimming and brightening or alternativelyturning on/off individually or in groups each of the lights in theplurality of lights 16.

The intensity of a portion of the plurality of lights 16 is dimmed orbrightened to anticipate the reflective effect of specular surfaces thatare inherent to the substrate 22, particularly at micro locations alongthe edge profile that have very small radii of curvature. These microlocations are the transition zones 33 where the top surface 24 meets thetop bevel 28 and the top bevel meets the crown 32 and the crown meetsthe bottom bevel 30 and the bottom bevel 30 meets the bottom surface 26.

An example of addressable illumination is illustrated in FIGS. 4 and 5where higher intensity illumination 36 is directed to a top bevel 28,crown 32 and bottom bevel 30 while lower intensity illumination 38 isdirected to the transition zones 33 in between. With this illuminationconfiguration, the image of these transition zones 33 are seenilluminated with similar intensity as compared to the top bevel 28,crown 32 and bottom bevel 30.

Further, addressable illumination is useful to accommodate intensityvariation seen by the optic 18 due to view factor of the substrate 22edge area. Some portions of the substrate 22 edge area have a high viewfactor with respect to the illumination from the diffuser 12 andconsequently appear relatively bright. Other portions with low viewfactor appear relatively dark. Addressable illumination allows mappingan intensity profile onto the wafer surface that allows for the viewfactor variation and provides a uniformly illuminated image. Therequired intensity profile can change with viewing angle change of theoptic 18.

Addressability of the illumination or its intensity can be accomplishedin a number of ways. One embodiment is to locate independentlycontrollable light-emitting diodes (LEDs) around the outside of thediffuser 12 consistent with the plurality of lights 16. Anotheralternative is to employ a small flexible organic light-emitting diode(OLED), liquid crystal display (LCD) or other micro-display module. Suchmodules are addressable to a much greater degree than an LED matrix. Inthis embodiment the flexible OLED, LCD or other micro-display module canreplace both the plurality of lights 16 and the diffuser 12. Forexample, a flexible OLED can both illuminate and have a surface layerwith a matte finish suitable for acting as a diffuser and neutralbackground for imaging. Further, the flexible OLED can be formed into asuitable shape such as a cylinder. Examples of a suitable OLED aredisclosed in U.S. Pat. Nos. 7,019,717 and 7,005,671, incorporated hereinby reference.

Further, those modules can also provide programmable illumination acrossa broad range of colors including white light. Color selection can beused to highlight different thin films and can be used in combinationwith part of an OLED, for example, emitting one color while another partof the OLED emits another color of light. In some cases it can bebeneficial to use only part of the light spectrum, for example, to gainsensitivity to a film residue in a given thickness range. This is onemode of analysis particularly applicable to automatic defectclassification. One analysis technique to detect backside etch polymerresidue preferentially looks at light reflected in the green portion ofthe spectrum. Thus, this embodiment of the system 10 provides for asuitable color differential based inspection of the substrate 22.

Now referring to FIG. 6, in another embodiment of the system 10, theoptic 18 is rotatable in a radial direction 40 around the substrate 22at a maintained distance from a center point of the substrate 22 edge.The optic 18 is rotatable while maintaining the angle of the optic 18relative to surface normal of the substrate 22 edge. This allows forfocused imaging of all regions of the substrate 22 surface, includingthe top surface 24, bottom surface 26, top bevel 28, bottom bevel 30 andcrown 32. The rotating optic 18 can also include the imaging system 20or consist of a lens and a CCD camera combination or can be a subset ofthis consisting of moving mirrors and prisms. This embodiment providesthe additional advantage of using one set of camera hardware to view thesubstrate 22 rather than an array of cameras.

Now referring to FIGS. 7 and 8, in another embodiment of the system 10,the optic 18 includes a fold mirror 50 and a zoom lens assembly 52. Theoptic 18 is connected to a rotatable armature 54 for rotating the optic18 radially around the edge of the substrate 22 (as similarly discussedin relation to FIG. 6). The substrate 22 is retained on a rotatablechuck 56. The diffuser 12 is housed in an Illumination cylinder 58 thatis retained on a support member 60 connected to a support stand 62.

The operation of this embodiment of the system 10 is substantially thesame as described above with the additional functionality of radiallymoving the optic 18 to further aid in inspecting all surfaces of theedge of the substrate 22. Further, the substrate 22 can be rotatedeither manually or automatically by the rotatable chuck 56 to facilitatethe inspection process.

Referring to FIG. 9 an automatic wafer edge inspection and review system10 consists of an illuminator 11, an optical imaging subsystem 64, awafer supporting chuck 66 (not shown), a positioning assembly 68, aneccentricity sensor 70, a linear stage 72, a rotary stage 74, and acontrol console 76. The eccentricity sensor 70 is used to provideeccentricity data to the controller to allow the controller topositionally adjust the substrate 22 with respect to the imaging system64. Optionally, data from the eccentricity sensor 70 can be used toadjust the optics system to ensure uniformity of the image and focus asopposed to or in conjunction with the supporting chuck 66.

Referring to FIG. 10 and as described above, the illuminator 11 providesuniform illumination across the five wafer edge regions: top near edgesurface 78, top bevel 80, apex 82, bottom bevel 84, and bottom near edgesurface 86, as show in FIG. 11. It is also envisioned the illuminator 11can vary the intensity or color of the illumination depending upon theexpected defect or substrate region. Additionally, the illuminator 11can individually illuminate different regions of the wafer. The lightcontroller received input from the system controller 76.

Referring to FIG. 12, the optical imaging subsystem 64 has a filter 121,a mirror 122, an attachment objective lens 123, a motorized focus lens124, a motorized zoom lens 125, and a magnifier lens 126, and a highresolution area scan color camera 127. The motorized focus lens 124automatically or manually sets best focus position before startingautomatic inspection and during the review process. The filter 121 canbe a polarizer, or optical filter which allows the passage ofpredetermined frequencies.

The motorized zoom lens 125 can be configured in the low magnificationrange for inspection purpose and high magnification range for reviewpurpose. As shown in FIG. 14, the positioning assembly 68 orientates theoptical imaging subsystem 64 to the predefined inspection angle 51. Toimprove the image, the optical imaging subsystem 64 is orientated insuch a way that its principal axis 128 preferably is kept from thenormal direction 191 of the wafer edge portion under inspection. Thelinear stage 72 moves the wafer from its load position to the inspectionposition, and also performs the eccentricity compensation to bring thewafer always to the best focus position during the image acquisitionperiod. While the rotary stage 74 rotates the substrate 22 along thecircumference direction in a step-and-stop manner, as shown in FIG. 15,it is envisioned a continuous rotation of the wafer is possible.

The control console 76 controls the system 10 via the tool controlsoftware. In this regard, the console 76 controls the motion of linearstage 72 and rotary stage 74, positioning the assembly 68 to theuser-defined inspection angle. The controller further presets themagnification of the motorized zoom lens 125 and focus position of themotorized focus lens 124, initializing the image acquisition timing andother essential functions to complete the automatic inspection of awafer using user-predefined routines. The control console 76 alsodisplays the acquired images and runs the defect inspection andclassification software, reporting the results files to a factoryautomation system.

Referring generally to FIG. 9 which shows the operation of oneembodiment, a substrate 22 is picked up from a FOUP (not shown) or anopen cassette (not shown) in the equipment front end module (not shown)by the transportation robot arm 27, placed onto the rotational table ofthe aligner (not shown). The aligner detects the center of the substrate22 as well as its notch, aligns the wafer to the center axis of therotational table. After alignment is completed, the transport robot arm27 picks up the substrate 22 from the aligner, places it onto the waferchuck (not shown) of the inspection and review system 10.

Then, the wafer is rotated and the eccentricity sensor 70 starts tomeasure the eccentricity of the wafer relatively to the spin center ofthe rotary stage 74. The eccentricity information is fed back to thecontrol console 76. At the same time, the positioning assembly 68 movesthe optical imaging subsystem 64 to the routine inspection angle. Thenthe linear stage 72 moves the substrate 22 to the inspection positionfrom the load position. The rotary stage 74 starts to move forward onestep (routine-defined angle) and stops completely. The illuminator 11 isturned on, and the camera 127 takes an image of the portion of the waferedge within the field of view of the optical imaging system 64. Aftercompletion, the rotary stage 74 rotates one more step, settling downcompletely. The linear stage 72 moves the substrate 22 to the best focusposition based on the eccentricity data stored in the control console76. During the movement of the stage 72, the control console 76downloads the previous images from the camera to the onboard memory andthe hard disk media. Then, the camera 127 takes the second picture ofthe wafer edge. The above steps are repeated until the region ofinterest or the whole circumference of the substrate 22 is imaged.

If the system is set to inspect the edge regions of substrate 22 in morethan one inspection angles, the control console 76 moves the positioningassembly 68 to another inspection angle, repeating the steps describedabove. The images of the edge of the substrate 22 at the new inspectionangle are recorded until all inspection angles of interest are covered.

After the completion of imaging all the predefined edge regions ofsubstrate 22, the transport robot arm 27 picks the substrate 22 from theinspection chamber, and place it back to a FOUP or a cassette in theequipment front end module.

While the system 10 takes pictures of the edge of substrate 22, theinspection and classification software installed in control console 76processes the raw images, detects the defects of interest, classifiesthem into different classes or category and outputs to the resultsfiles. To review a specific defect found by the system 10, the locationand the inspection angle of the specific defect can be retrieved fromthe results files. As shown in FIG. 16, an operator inputs thisinformation to the review system setup area of tool control software inthe control console 76. The control console 76 automatically moves thesubstrate 22 and the positioning assembly 68 to the predeterminedpositions, locates the specific defect of interest. Then, the useradjusts the magnification of the motorized zoom lens 125 to the desiredvalue, focusing on the defect by adjusting the position of the motorizedfocus lens 124. The operator can now review the details of the defect onthe display and record its image to storage devices of the controlconsole 76.

Referring to FIGS. 9 and 18, the system is used to measure the cut line141 of the edge bead removal of a film layer 140. The positioningassembly 68 moves the optical imaging subsystem 64 and the area scancamera 127. In this position, the top near edge surface of the substrate22 with the cut line 141 is visible within the field of view. Themotorized focus lens 124 is set to the position where the image is underbest focus. The rotary stage 74 starts to move forward one step(predefined angle) and stops completely. The illuminator 11 is turnedon, and the camera 127 takes an image of a portion of the near top edgesurface including the cut line 141. Then, the rotary stage 74 moves onemore step, settling down completely. While the stage is in motion, thecontrol console 76 downloads the image from the camera 127 to theonboard memory and the hard disk media. Upon completion, the camera 127takes the second picture. The above steps are repeated until the wholecut line along the circumference of the substrate 22 is completelyimaged and recorded onto onboard memory and the hard disk media.

During operation, the control console 76 processes the recorded imagesto calculate the profile of the cut line 141 as well as the followingparameters: the center disposition from the wafer center, mean edgeexclusion distance, the standard deviation, and the peak-to-peakvariation. The results are output to the results file with predefinedformat.

As shown in FIGS. 9 and 19, the wafer edge inspection and review system10 can be used to measure multiple cut lines, for example, 151, 152, and153 of multiple film layers 154,155, and 156. The positioning assembly68 moves the optical imaging subsystem 64 and the area scan camera 127to a position so that the top near edge surface of the substrate 22 withthe cut lines 151, 152 and 153 is within the field of view. Themotorized focus lens 124 is set to the position where the image is underbest focus. The rotary stage 74 starts to move forward one step andstops completely. The illuminator 11 is turned on, and the camera 127takes an image of a portion of the near top edge surface including thecut lines 151, 152 and 153. Then, the rotary stage 74 moves a secondstep, settling down completely. While the rotary stage is in motion, thecontrol console 76 downloads the picture from the camera 127 to theonboard memory and the hard disk media. Upon completion, the camera 127takes the second picture. The above steps are repeated until the wholecut lines along the circumference of the substrate 22 are completedimaged and recorded onto onboard memory and the hard disk media.

It should be appreciated that while the embodiments of the system 10 aredescribed in relation to an automated system, a manual system would alsobe suitable. This includes a hybrid automated/manual inspection withautomated or manual defect classification as described in U.S.Provisional Patent Application ______, filed Aug. 9, 2007, entitled“Apparatus and Method for Wafer Edge Defects Detection” and U.S.Provisional Patent Application ______, filed Aug. 9, 2007, entitled“Apparatus and Method for Wafer Edge Exclusion Measurement”, bothincorporated herein by reference. This also includes automatedinspection in conjunction with automated wafer handling includingrobotic wafer handling with wafers delivered via FOUP or FOSB.

Thus, a cost effective yet efficient and effective system is providedfor illuminating and inspecting the plurality of surfaces of the edgearea of a substrate 22 and providing high quality imaging of theinspected surfaces while avoiding the interference associated withspecular surfaces. The system provides for improving quality control ofwafer processing through edge inspection with the intended benefit ofidentifying and addressing defects and their causes in the ICmanufacturing process with resulting improvement in yield andthroughput.

1. An automatic wafer edge inspection and review system comprising: anilluminator configured to provide illumination across a wafer edge; anoptical imaging subsystem to image a portion of the wafer edge; apositioning assembly to orientate the optical imaging subsystem to aninspection angle; an eccentricity sensor to actively measure the centeroffset of a wafer edge relative to the rotation center of the waferchuck; and a wafer chuck to hold the backside of a wafer.
 2. The systemof claim 1 wherein the optical imaging subsystem further comprises anoptical filter to cut off certain wavelength spectrum; a mirror; anobjective lens; a motorized focus lens to provide routine-defined focusadjustment; a motorized zoom lens; a magnifier lens; and a highresolution area scan color camera to image a portion of the wafer edge.3. The system of claim 1 wherein the illuminator comprises, acylindrical light diffuser having a slit extending at least a portion ofits length for receiving an edge portion of a wafer; a plurality oflight sources exterior or interior to the cylindrical light diffuser;and an intensity controller for independently controlling the pluralityof light sources.
 4. The system of claim 1 wherein the optical imagingsubsystem is orientated in such a way that its principal axis is alwayskept away from the normal direction of the wafer edge portion underinspection.
 5. The system of claim 1 further comprising a rotary stagewhich rotates the wafer in a step-and-stop fashion; a control console toprovide tool control functions, image display, defect inspection, defectclassification and edge exclusion measurement capabilities.
 6. Thesystem of claim 5 wherein the eccentricity sensor measures theeccentricity of a wafer and provides a signal to the control console. 7.The system of claim 5 wherein the rotary stage rotates the wafer alongthe circumference direction in a step-and-stop manner.
 8. The system ofclaim 6 wherein the linear stage performs the eccentricity compensation,and brings the wafer to a best focus position based on the signal fromthe eccentricity sensor.
 9. The system of claim 5 wherein the controlconsole performs automatic defect inspection and classification,automatic measurement of edge bead removal cut lines and semi-automateddefect review.
 10. The system of claim 2 wherein the filter is apolarizer.
 11. An automatic wafer edge inspection and review system ofclaim 1 wherein the wafer chuck is a pin-chuck and wafer is held on topof a plurality of pins by vacuum.
 12. A wafer edge illumination andinspection system comprising: a light diffuser having a slit extendingat least a portion of its length for receiving a portion of a waferincluding a portion of the wafer edge; a plurality of light sources inproximity to the light diffuser; and an optical imaging subsystem forviewing the wafer wherein the optic is exterior of the light diffuser,and is positioned at an angle off a wafer edge surface normal, whereinthe optical imaging subsystem further comprises an optical filter to cutoff certain wavelength spectrum, a mirror, an objective lens, amotorized focus lens to provide routine-defined focus adjustment, amotorized zoom lens, a magnifier lens, and a high resolution area scancolor camera to image a portion of the wafer edge.
 13. The wafer edgeillumination and inspection system of claim 12 further comprising: anillumination control system for independently controlling the pluralityof light sources.
 14. The wafer edge illumination and inspection systemof claim 12 further comprising: a rotation mechanism for rotating theoptic radially relative to a center point of the wafer edge region. 15.The wafer edge illumination and inspection system of claim 12, whereinthe light diffuser is a quartz tube.
 16. The wafer edge illumination andinspection system of claim 12, wherein the plurality of light sources isan LED matrix.
 17. The LED matrix of claim 16 wherein each LED isindependently controllable.
 18. The wafer edge illumination andinspection system of claim 12, wherein the plurality of light sources isan array of fiber optics each coupled to an independent remotely locatedlamp.
 19. The array of fiber optics of claim 18 wherein each lamp isindependently controllable.
 20. The wafer edge illumination andinspection system of claim 12, wherein the plurality of light sources isan LCD matrix.
 21. The wafer edge illumination and inspection system ofclaim 12, wherein the plurality of light sources is a flexible OLED. 22.A substrate imaging system for imaging a specular surface of asubstrate, comprising: a light diffuser housing having an opening forreceiving a portion of the substrate wherein the interior of the lightdiffuser housing is a uniform neutral background to a specular surfacebeing imaged wherein the light diffuser housing extends from over a topsurface of the wafer to over an edge of the wafer and over a bottomsurface of the wafer; an optical subsystem angled off a surface normalof the substrate area to be imaged wherein the optical lens is exteriorto the light diffuser, wherein the optical subsystem comprise, a mirror,an objective lens, a motorized focus lens to provide routine-definedfocus adjustment, a motorized zoom lens to provide both inspection andreview functions, a magnifier lens, and a high resolution area scancolor camera to image a portion of wafer edge; a light source disposedin the light diffuser housing; and an eccentricity sensor to activelymeasure the center offset of a wafer edge relative to the rotationcenter of the wafer chuck.
 23. The substrate imaging system of claim 22wherein the light source is coupled to a fiber optic for directing lightfrom the light source to a plurality of locations of the light diffuserhousing.
 24. The substrate imaging system of claim 22 wherein the lightsource is one selected from the group of an LED matrix, LCD matrix, andOLED.
 25. The substrate imaging system of claim 22 further comprising alight controller for controlling the color and brightness of the lightsource.
 26. The substrate imaging system of claim 16 wherein the lightsource is one selected from the group of an LED matrix, LCD matrix, andOLED, wherein the light diffuser housing is a covering attached to thelight source.